There is an increased emphasis on the use of unmanned air vehicles (UAVs) for performing various activities in both civilian and military situations where the use of manned flight vehicles may not be appropriate. Such missions include surveillance, reconnaissance, target acquisition, target designation, data acquisition, communications relay, decoy, jamming, harassment, ordinance delivery, or supply.
Airborne surveillance systems typically include one or more unmanned aircraft each carrying one or more sensors for detecting, imaging or monitoring target items in an area under surveillance. Electro-optical or infrared (EO/IR) sensors can provide high resolution images. However, if clouds obscure the target, EO/IR sensors will not be able to image the target. Synthetic aperture radar (SAR) sensors can penetrate clouds but provide lower resolution images.
The communications devices used in the surveillance system may be bandwidth limited. That is, there may not be enough bandwidth to download imagery from all the sensors at the same time. In addition, electro-optical and infrared cameras may share the same set of lenses to reduce payload weight. In that case, only one EO or IR sensor may be used at a time. Even if all sensors could be used concurrently, there may be limited staff on the ground to evaluate the images; so all downloaded imagery should be the highest quality possible.
If the unmanned aircraft could automatically detect the presence of clouds, the type of sensor that is most appropriate for imaging could be selected. Thus there is a need for a method and apparatus for automatically detecting the presence of clouds from an unmanned aircraft.